1. Field of the Invention
The present invention relates to a substrate processing apparatus for performing a predetermined liquid process, such as a cleaning process, on a substrate, such as a semiconductor wafer.
2. Description of the Related Art
In the process of manufacturing semiconductor devices or flat panel display devices (FPD), liquid processes are frequently used, in which a process liquid is supplied onto a target substrate, such as a semiconductor wafer or glass substrate. For example, a process of this kind is a cleaning process for removing particles and/or contaminants deposited on a substrate.
As a substrate processing apparatus used for this purpose, there is known an apparatus that performs a cleaning process on a substrate, such as a semiconductor wafer, held on a spin chuck, in which a process liquid, such as a chemical liquid, is supplied onto the substrate, while the substrate is rotated. In general, according to apparatuses of this kind, a process liquid is supplied onto the center of a substrate, and the substrate is rotated to spread the process liquid outward, thereby forming a liquid film and throwing off the process liquid out of the substrate. After the cleaning process, a rinsing process is performed, such that a rinsing liquid, such as purified water, is supplied onto the substrate, while the substrate is rotated in a similar way, thereby forming a liquid film of the rinsing liquid and throwing off the rinsing liquid out of the substrate. In light of this, there is proposed a structure in which a drain cup is disposed to surround a substrate and to receive and discharge a process liquid or rinsing liquid thrown off outward from the substrate (for example, Jpn. Pat. Appln. KOKAI Publication No. 2002-368066).
According to this substrate processing apparatus, a substrate is rotated to throw off the process liquid or rinsing liquid outward from the substrate by a centrifugal force, while gas is exhausted from around the substrate, so that the process liquid or rinsing liquid is collected.
However, if the exhaust power is insufficient, mist is generated above the substrate and particles are thereby deposited on the substrate.